Method of recovering oxalic acid



1 the manufacture of iulminate UNELEEE EDWARD A. BARNES, OF OAKLlND, CALIFORNIA, ASSIGNGIZ Ti? CAZJIFQPEYIJL 630311- PAIJY, F OAKLAND, CALIFGRNIA, A. CQIRFQRATZSN 0F (1&

Ho Drawing.

continuation in part of my copen-ding application entitled, Method and apparatus for of mercury and the YfiCOYQSY of oxalic acid, filed April 3, 1922. Serial No. 5%,921?

The residual liquors obtained during the iizictuie of fulzninate of nieiciiiy, oi? filie liiliiiinziie is manufacture umier the Ulicncleloiis process or oilicr'wise,

lime generally been considered 21. Waste anti as such have been thrown away. The large miantities of s te liquors IQSH iZlTLg from t e manufacture of fuiminate of mercury by the process described in my copencling application above referred to, provided quite a problem when their proper disposel Wes coiisideie i and resulted in investigasioiis which conclusively proved that oxalic ziciii in paying quantities could be obtained. The actual yield of oxalic acid was found in some instances to approximate of the fulmimite produced and is, obviously, a consifierable item when Working on 21 large scale.

According to the present invention the recovery or production of oxalic acid from the Waste liquors is accomplished follows? The residual liquors resulting from the recess of manufacturing fulmi'nete of mernry contain a large proportion of glycolic cid. together with free nitric acid, This iquoi is filtered and placed in on evepomtoc here it is retliicecl to approximately one eighth it s original bulk, any suitable type evaporator being emoloycd, or it may be reduced by evaporation until its 5 ccific gravity approximates 1.200. Oxidation of the glycolic acid to oxalic acid takes place during evaporation and the oxalic ccial crystallizes out in Well. formed crystals when the liquor is cool. Theo stols are tlien filteretl out aml by washing; i. e some with 2. small Application filed January 2, 1923.

amountof Water, gareiercbly centrifugal by means of a spray, ell adhering impurities are IQll'lOVMl anti ii. product substantially 99-16 0 pure is obtainee without further yecrystallization. Further concentration of. the mot 1E1 liquors will yield small amount of oxalic acid more or less impure and may be resorted to if desired;

The yield oi": oxalic ecizi from ilie first crystallization is approximately of the total amount of fulminzite procliicei'l anti as a small amount of oxalic cm! ed led thereto by further concei i the mother liquors, the final aiiioimi. if oxalic acid obtained is, obviously, a \Iierolile item when 'WOl'lililg on o ieige scale, and as such forms 9. valuable ay-precinct: when the "manufacture fulmineieoi memos-y is con? siderecl.

Having thus my ioveiicioo, What I claim and desire to secure lo}? Lester-s Foo ent is-- l. The production of oxalic the waste liquo obtained dilllilg? ture of ifiilmiiiate momm consisls iii subfecting the z'esidiial liquors to evaporation end oxidation of ilie glycolic acid to oxalic acid.

2. The production of oxalic eci l fs'om the Waste liquors obtained {losing the meoufec ture of fulminaic of merciiiw', w ll consists in subjeetiiig the residual liquors tion and oxidation of he giyco acid to oxalic acid, crysialliziiig one 0 lie ELClil,

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and then reeioviog the ciystols 15mm the remaining liqueix.

3. The p'i'oiiuc ion or? c ic iii an the wcsce liquors cit-mined ture of 'liilmimte of mercury, Wl'lieli Isis in subjecting shx residual iioiio. s to e's'ageoietime anal mile Lion the glycelic acid, anal then cooling the liquor to Pfii'ilhfi crysteilicsv lion of the i lll'fl to place,

i. The moecitioe of oxalic from the wasie. liquors obtained diiiiiig; meme :fecture oil? iclmiziate oi mercuiy which cow sists in filie iresicliiel liquors to evaporation until the specific of the li uor eporoximetee lfC O fjxlfilziilgllllfi glycoic acirl, anti tlieiicoolmg time liquor to permic the oxalic cciol 1o crystallize.

FLTZEEWAL A. Eiifillldil. 

